Catalytic processes play a heavy role in refining carbonaceous materials. Likewise, regeneration of the involved catalyst logically occupies a correspondingly large amount of a process engineer's time and efforts. For example, in the conversion of high-boiling non-gasoline hydrocarbons into lower boiling gasoline components, the catalytic-aided process steps of treating, decomposition, fractionating, gasoline stabilization, and absorption polymerization requires, for the most part, cyclic or occasional regeneration of the involved catalysts, see, for example, Kirk-Othmer, Encyclopedia of Chemical Technology, 2nd Edition, Volume 15, "Petroleum (Refinery Processes)", page 15 et seq.
Catalysts are usually classified by function--fixed bed, movable bed, or fluid bed--and by process condition, three typical process examples being set forth below to better illustrate the practice of catalyst-aided processes in general and the regeneration of involved catalyst in particular.
1. Early catalytic crackers were usually of the fixed bed type but today most cracking is carried out in moving or fluid beds. Regeneration temperatures and pressures in moving and fluid beds are usually in the ranges of 1,000.degree.-1,210.degree.F and 8 to 30 psig, respectively,
2. Modern hydrocrackers employed in hydrocracking (an efficient low-temperature catalytic method for converting refractory middle-boiling or residue streams to high-octane gasoline or jet fuel, etc.) use fixed bed processing for the most part. After hydrogen has been mixed with the feed, the mixture is heated and contracted with a catalyst in a separate fixed-bed reactor at specified hydrogen partial pressures. Regeneration pressure and temperature of the catalyst are usually within the ranges of 400.degree. to 800.degree.F and 10 to 2,000 psig, respectively, and
3. Modern catalytic reformers associated with catalytic reforming (upgrading naphthas into high-grade components for fuel blending or petroleum usage in which molecules are rearranged to give a higher antiknock quality at the expense of yield) also employ fixed beds in the main, e.g., less than 5% of the U.S. reforming capacity, it is estimated, utilizes fluid or moving bed processes. Temperature and pressures for regeneration of catalyst involved in reforming are in the ranges of 800.degree. to 1,500.degree.F and 200 to 400 psig, respectively.
In controlling regeneration temperature and pressure conditions within the above processes, it has been found that the aforementioned variables are usually not monitorable in a direct fashion. Safe engineering practice dictate against the use of internal sensors, for the most part, because associated control and energization elements must, in some manner, penetrate the sidewalls of the vessels undergoing regeneration. Instead, temperatures and pressures of associated regeneration fluids flowing relative to the vessel are monitored. Temperatures of the catalytic regeneration process are then inferred from temperature and pressure values measured at external sensing locations.
Although infrared scanning techniques have been used in many refinery applications, such applications of which we are aware, have been limited in scope and function. Moreover, such techniques were thought not to have the capability of monitoring regeneration processes to which the present invention is directed since such vessels are for the most part heavily clad with insulation. Thus, metallic sidewalls (which could be associated with interim regeneration temperature characteristics) are almost totally hidden from camera view, especially if such camera units are remotely located within an aircraft overflying the vessel undergoing regeneration under conditions that are conductive to atmospheric degradation ("clutter") and image blur of the emitted infrared energy.